In preventing airplane corrosion, there has developed a requirement to apply an anti-corrosive sealant between rivets and the rivet securing member, such as the skin of the plane. This can be achieved by injecting the sealant into the rivet holes and then inserting the rivets, a process that is presently performed by hand. Because thousands of rivets are inserted into an airplane wing, the aircraft industry is employing the use of automated rivet machines, with corresponding automated sealant applicators.
Most rivets have a tapered head which require a countersink in the rivet hole. To obtain a complete seal, it is necessary to have sealant cover the entire circumference of the countersink. Present applicators inject a ring of sealant "balls" that are spread around the countersink when the rivet is pressed into the hole. To insure complete coverage of the countersink, an excess amount of sealant is injected into the rivet hole. If too much sealant becomes entrapped between the countersink and the rivet, the sealant will exert a hydraulic pressure on the rivet, pushing the rivet out of the rivet hole. In addition, the excessive sealant squeezes onto the surface of the wing, requiring an additional step of removing the excess sealant, a time consuming process presently performed by hand. Thus there is a need for a sealant applicator to provide an exact amount of sealant that uniformly covers the circumference of a rivet hole.
Present nozzles include a spring return tip attached to the nozzle housing, where the amount of sealant ejected is adjusted by rotating the tip within the housing. Self-turning of the tip during an automated cycle of riveting, causes inconsistent ejections of sealant, resulting in rivets with excessive or inadequate amounts of sealant. It is therefore desirable to have a nozzle with means to prevent tip rotation within the housing, during sealant operations.